When functioning properly, the human heart maintains its own intrinsic rhythm based on physiologically-generated electrical impulses. It is capable of pumping adequate blood throughout the body's circulatory system. Each complete cycle of drawing blood into the heart and expelling it is referred to as a cardiac cycle.
However, some people have abnormal cardiac rhythms, referred to as cardiac arrhythmias. Such arrhythmias result in diminished blood circulation. Arrhythmias can occur in the upper chambers of the heart—the atria, or the lower chambers of the heart—the ventricles. However, ventricular arrhythmias present the most serious health risk as they can lead to rapid death from the lack of circulation. Arrhythmias are further subdivided into specific conditions of the heart that represent vastly different manifestations of abnormal cardiac rhythm. These conditions are bradycardia, or a slow heartbeat, and tachycardia, or a fast heart beat. Fibrillation and flutter, which are essentially random and incoherent heart twitches where no pumping action is occurring at all, are potentially the most serious arrhythmias.
Increasingly, clinicians use implantable medical devices (“IMDs”) to monitor and control arrhythmias. IMDs include pacemakers, also referred to as pacers, and defibrillators. A traditional use of a pacemaker is to treat bradycardia by stimulating cardiac rhythm. Pacers accomplish this by delivering timed sequences of low energy electrical stimuli, called pace pulses, to the heart. Such stimuli are delivered via an intravascular lead wire or catheter (referred to as a “lead”) having one or more electrodes disposed in or about the heart.
In comparison to a pacemaker, an implanted defibrillator applies a much stronger electrical stimulus to the heart. This is sometimes referred to as a defibrillation countershock, also referred to simply as a “shock.” The shock changes ventricular fibrillation to an organized ventricular rhythm or changes a very rapid and ineffective cardiac rhythm to a slower, more effective rhythm. Defibrillators help treat cardiac disorders that include ventricular fibrillation, ventricular tachycardia, atrial fibrillation, and atrial flutter. These inefficient or too rapid heartbeats reduce the pumping efficiency of the heart and thereby diminish blood circulation. The countershock delivered by the defibrillator interrupts the tachyarrhythmia, allowing the heart to re-establish a normal rhythm for the efficient pumping of blood.
Another mode of treating a cardiac arrhythmia uses drug therapy. Drugs are often effective at restoring normal heart rhythms. However, regardless of the method used to treat an arrhythmia, the therapeutic goal is to convert the irregular heartbeat into a normal or more regular pattern.
Modern IMDs can separately sense and coordinate the contractility of both the upper (atria) and lower (ventricles) chambers of the heart and serve as dual pacer/defibrillators. IMDs can further serve as a component of a comprehensive patient management system for predictive management of patients with chronic disease.
Presently, even the most basic IMDs typically have more than one arrhythmia detection criterion—tiered therapy which combines bradycardia support pacing with various antitachycardia pacing modes, low-energy cardioversion, defibrillation, and data logging capabilities. The data logging capabilities of IMDs have become increasingly important, since the amount of data required for the IMDs' operation increases proportionally with the increase in IMD functions. Efficiently processing this large amount of data has become possible with the incorporation of microprocessors and memory with the IMD.
Once an IMD has been implanted, the clinician interacts with the IMD through a clinical programmer. The clinical programmer is used to establish a telemetric link with the implanted IMD. The telemetric link allows for instructions to be sent to the electronic circuitry of the IMD and clinical data regarding the occurrence and treatment of a patient's cardiac arrhythmias and the IMDs operation to be sent from the electronic circuitry of the IMD to the programmer. The typical programmer is a microprocessor based unit that has a wand for creating the telemetric link between the implanted IMD and the programmer, and a graphics display screen that presents a patient's recorded cardiac data and IMD system information to the physician.
With implantable medical devices now capable of conducting sophisticated monitoring and treatment of cardiovascular disease, configuring the device has become increasingly critical to treatment efficacy and patient safety. A programmer allows the clinician to configure the device to meet these goals. In addition, because of rapid advances in computer technology, clinicians now have sophisticated programming tools capable of non-invasive programming and display of medical data in graphic and alpha-numeric forms.
As computer technology left the domain of esoteric scientific research and became accessible to non-computer experts for everyday use, alpha-numeric systems were typically the only way to program computer operation. Typically, a computer user would type a character string to program the computer to perform a specific function and then be limited to an alpha-numeric display of the computer's output.
As IMD feature sets become richer and more complex, IMDs are getting increasingly more complicated to program. This is especially the case in situations where modifications of one feature ripples through and interacts with other selected features.
For IMDs it can be very difficult for clinicians to deal with non-compatibilities with a programmer's features. Such devices may have many features to program and, when clinician attempts to program an IMD through a programmer, there may be some inconsistencies that are not allowed by logic or because of concerns for the patient's safety. In the past, these inconsistencies were displayed as error messages and the clinician often had to wade through a series of screens to determine the nature of the inconsistency and how to resolve it.
In addition, clinician were frustrated by error messages, which noted an interaction but did not tell the clinician what to do to resolve the problem. Clinicians were often reduced to trial and error programming which might create a second parameter interaction while resolving the first.
Programmers also have other limitations. Typically, IMD parameters were set by selecting from a list of possible options via the programmer. However, the options were often scattered throughout the programmer user interface.
However, as computer processing, memory and display systems improved, operating systems were developed that allowed the clinician to program an IMD by using a programmer with a graphical interface. In addition, clinicians could view computer output graphically. This gave clinicians greater control over computer functions and to recognize and analyze trends in computer output data more efficiently.
The first graphical user interface (“GUI”) has been attributed to Xerox Corporation's Palo Alto Research Center in the 1970s, but it was not until the 1980s when graphical user interfaces became commercially feasible and popular. In addition to their visual components, graphical user interfaces used as medical tools make it easier to manipulate data in creative ways to gain different perspectives and a better understanding of the data's clinical significance.
For implantable medical devices, one way to manipulate the data perspective of the device is through the use of a programmer that employs a GUI. Programmer systems for implantable medical devices now use GUIs to graphically visualize the programming process and results. The obvious advantage of a GUI system over an alpha-numeric system is the ability to visually analyze the device's operation and the patient's medical data through the interface. In this way, the device is easier to use and configure, and provides the clinician with a better understanding of the therapies available to the patient and the data relative to the device. In sum, such a programmer allows the clinician to track and monitor the status of the IMD and the data it collects.
The use of graphics in the diagnosis and treatment of disease increases the clinician's ability to interface and understand the many parameters that can be changed to customize the device's therapy to the patient's specific needs and to analyze large amounts of medical data. Such graphics may include line graphs, bar charts, pie charts, dialog boxes, meters, color charts, the use of color, analog and digital representations, icons, symbols, buttons, etc.
One such GUI-based programmer is the ZOOM™ programming system by Guidant. It employs a GUI that improves the speed, precision and easibility of programming an implantable medical device and enables clinicians to make better decisions, faster. Thus, fast accurate decisions can be achieved with GUIs that improve the way graphical data is presented to the clinician and are configurable for more precise clinical evaluations or diagnoses.
However, a needed improvement is a more intuitive way for the physician to resolve parameter interactions and a user interface that allows related parameters to be displayed simultaneously to enhance the clinician's resolution of parameter interaction conflicts and the impact of programming on patient health. For example, GUIs should be capable of visualizing cardiovascular events, therapeutic interventions or device operation quickly and efficiently to focus a clinician's attention on potential problems. In addition, GUI-based programmers should assist the clinician in analyzing the large amount of patient data monitored and recorded by the device. In this way, the GUI-based programmer empowers the clinician to effectively manage patient therapy through the medical device. GUI-based programmers should also allow the clinician to analyze device operation within the context of physiological parameters like the anatomy of the heart. When testing or evaluating the implantable medical device's operation or function, a GUI-based programmer should be capable of visually guiding the clinician through the steps of the process so the clinician is fully aware of what is taking place and when. In addition, a GUI-based programmer should have a graphically-based safety feature that prevents a clinician from making an inadvertent and potentially dangerous change to the device's operating parameters.
Thus, for these and other reasons, there is a need for a GUI-based programmer for an implantable medical device that improves the tasks of: (1) alerting the clinician to potential problems with the patient's condition or the therapy provided by the device or the device itself; (2) efficiently and effectively managing patient therapy; and (3) efficiently and effectively managing device operation without compromising patient safety.